Berlin 2024 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 13: Glasses and Glass Transition (joint session CPP/DY)
CPP 13.3: Vortrag
Montag, 18. März 2024, 17:00–17:15, H 0107
What can MD simulations tell us about the micromechanics of deformation of glassy amorphous polymers? — •Pramod Kumar Patel1 and Sumit Basu2 — 1Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, India — 2Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, India
Under uniaxial compression, the stress-strain responses of glassy amorphous polymers exhibit a yield drop followed by hardening at large strains. The extent of the yield drop and the steepness of the hardening response seem connected to the polymer's molecular architecture. Moreover, these materials exhibit strain rate sensitivity, pressure-dependent yielding, and somewhat peculiar unloading behaviour. The connections between the molecular architecture of the glassy amorphous polymer and its uniaxial compressive response are not well understood.
Micromechanically motivated constitutive models proposed by various authors are often able to negotiate many of the subtle aspects of the stress-strain behaviour but need to incorporate several fitting parameters to do so. We attempt to probe the physical processes and the effect of the underlying macromolecular force fields that lead to the typical stress-strain response through well-designed molecular dynamics (MD) simulations. Moreover, using a recently developed probe for quantifying the entanglement structure of the polymer, we show that the large strain uniaxial behaviour is governed by disentanglements and entanglement slips that invariably accompany deformation.
Keywords: Glassy polymers; Molecular dynamics; Constitutive models; Entanglement; Uniaxial compression